Hitherto, a display device has been used in various apparatuses such as an electronic timepiece.
In a portable electronic apparatus disclosed in JP-A-2004-178029, the power consumption of a self-luminous type (current driving type) display panel is reduced by reducing the number of dots of a display font when a battery voltage is lowered (normally, 5*10 dots are used, but 5*5 dots are used when the battery voltage is lowered).
In the self-luminous type display panel such as an EL (Electro-luminescence) display panel, the power consumption can be reduced in this way. However, as for a liquid crystal display (LCD) of a reflective display panel, there is a limit in reducing the power consumption since a turn-off signal is output even to cells not being displayed.
For example, in an electronic timepiece having an LCD display section according to the related art, as shown in FIG. 18, there is a limit to reducing the power consumption even when only a charge mark blinks to prompt a user to execute charging in a case where the remaining capacity of a battery becomes low. This is because the turn-off signal is output even to the cells not being displayed.
FIG. 18 is a diagram illustrating an LCD display section of an electronic timepiece having an azimuth display function. A display component is separated into three display blocks A, B, and C. The display block A is a mark display block that displays the remaining battery level. The display block B is a clock time display block that is used when a time or the like is displayed. The display block C is an azimuth display block that displays an azimuth. Common terminals COM0 to COM7 driven at a predetermined period (in other words, a predetermined duty ratio) are connected to the display components of the display blocks A to C. Segment terminals SEG00 to SEG01 are connected to the display components of the display block A, segment terminals SEG02 to SEG51 are connected to the display components of the display block B, and segment terminals SEG52 to SEG63 are connected to the display components of the display block C.
In FIG. 18, the display blocks A and B are driven in a turn-on state and the display block C is driven in a turn-off state. In this case, all of the common terminals COM0 to COM7 are driven at a predetermined period. On the other hand, the segment terminals SEG00 to SEG51 of the display blocks A and B are driven in a turn-on state. In addition, the segment terminals SEG52 to SEG63 of the display block C are driven in the turn-off state by a turn-off signal. Thus, the display components of the display blocks A and B are turned on and the display components of the display block C are turned off. However, since the segment terminals SEG52 to SEG63 of the display block C are driven by the turn-off signal, it is difficult to reduce the power consumption.
In a multilayer liquid crystal timepiece disclosed in JP-A-54-45169, independent LCDs are provided, displays for the normally displayed hours, minutes, and seconds are disposed externally, and a calendar display called as necessary is disposed internally, so that visibility of a typical timepiece can be realized normally by the displays for hours, minutes, and seconds.
However, since the turn-off signal is output even to the cells not being displayed, there is a limit to reducing the power consumption.
Likewise, an LCD driving signal may not be separated in an electronic azimuth-finder-mounted wristwatch, in which a time display LCD and an azimuth display LCD overlap with each other, or an electronic azimuth-finder-mounted wristwatch, in which azimuth display cells are disposed around a display region (see JP-A-3-262918). Therefore, since the turn-off signal is output to the azimuth display LCD panel even while an azimuth display is not performed, there is a limit to reducing the power consumption.
In a radio wave reception device disclosed in JP-A-2009-145210, a liquid crystal display panel is separated into two regions, an antenna is disposed below a first display region, and display driving of the first display region is stopped during reception of standard radio waves, so that the antenna blocks the influence of noise from the LCD. By controlling a first display driving circuit section 207 and a second display driving circuit section 208, it is possible to independently control the first and second display regions.
The power consumption can be reduced by stopping the display driving of the first display region. However, since the number of cells in the first display area and the number of cells of the second display area are fixed, a problem may arise in that it is necessary to develop a dedicated LSI (Large Scale Integration Circuit) for each kind of device even when display forms are different.